Return-Path: Received: from mtain-md06.r1000.mx.aol.com (mtain-md06.r1000.mx.aol.com [172.29.96.90]) by air-mf10.mail.aol.com (v128.1) with ESMTP id MAILINMF102-8bfe4bbb050a1cc; Tue, 06 Apr 2010 05:55:22 -0400 Received: from post.thorcom.com (post.thorcom.com [193.82.116.20]) by mtain-md06.r1000.mx.aol.com (Internet Inbound) with ESMTP id 1867038000053; Tue, 6 Apr 2010 05:55:19 -0400 (EDT) Received: from majordom by post.thorcom.com with local (Exim 4.14) id 1Nz5U6-0007eB-Pv for rs_out_1@blacksheep.org; Tue, 06 Apr 2010 10:54:14 +0100 Received: from [193.82.116.32] (helo=relay1.thorcom.net) by post.thorcom.com with esmtp (Exim 4.14) id 1Nz5U6-0007e2-1w for rsgb_lf_group@blacksheep.org; Tue, 06 Apr 2010 10:54:14 +0100 Received: from cavuit01.kulnet.kuleuven.be ([134.58.240.43]) by relay1.thorcom.net with esmtp (Exim 4.63) (envelope-from ) id 1Nz5U4-0002C2-DO for rsgb_lf_group@blacksheep.org; Tue, 06 Apr 2010 10:54:14 +0100 Received: from smtps01.kuleuven.be (smtpshost01.kulnet.kuleuven.be [134.58.240.74]) by cavuit01.kulnet.kuleuven.be (Postfix) with ESMTP id BD2947B805F for ; Tue, 6 Apr 2010 11:54:00 +0200 (CEST) Received: from ICTS-S-HUB-N3.luna.kuleuven.be (icts-s-hub-n3.luna.kuleuven.be [10.112.9.13]) by smtps01.kuleuven.be (Postfix) with ESMTP id 6DCED31E703 for ; Tue, 6 Apr 2010 11:54:00 +0200 (CEST) Received: from ICTS-S-EXC2-CA.luna.kuleuven.be ([10.112.11.13]) by ICTS-S-HUB-N3.luna.kuleuven.be ([10.112.9.13]) with mapi; Tue, 6 Apr 2010 11:54:00 +0200 X-Kuleuven: This mail passed the K.U.Leuven mailcluster From: Rik Strobbe To: "rsgb_lf_group@blacksheep.org" Date: Tue, 6 Apr 2010 11:53:59 +0200 Thread-Topic: LF: RE: RE: W1VLF 9 Khz Antenna update Putting inductance near the top. Thread-Index: AcrVa3Y6H5gvjNIJRgmxa+p2FOmDswAAuCTu Message-ID: References: ,<4BBAFE41.4020401@iup.uni-heidelberg.de> In-Reply-To: <4BBAFE41.4020401@iup.uni-heidelberg.de> Accept-Language: nl-NL, nl-BE Content-Language: nl-BE X-MS-Has-Attach: X-MS-TNEF-Correlator: acceptlanguage: nl-NL, nl-BE MIME-Version: 1.0 X-KULeuven-Information: Katholieke Universiteit Leuven X-KULeuven-Scanned: Found to be clean X-KULeuven-Envelope-From: rik.strobbe@fys.kuleuven.be X-Spam-Score: 0.0 (/) X-Spam-Report: autolearn=disabled,HTML_MESSAGE=0.001 Subject: RE: LF: RE: RE: W1VLF 9 Khz Antenna update Putting inductance near the top. Content-Type: multipart/alternative; boundary="_000_BF4A524700075746A6467658DFC7102C19A043E51EICTSSEXC2CAlu_" X-Spam-Checker-Version: SpamAssassin 2.63 (2004-01-11) on post.thorcom.com X-Spam-Level: X-Spam-Status: No, hits=0.6 required=5.0 tests=HTML_20_30,HTML_FONTCOLOR_BLUE, HTML_MESSAGE,TO_ADDRESS_EQ_REAL autolearn=no version=2.63 X-SA-Exim-Scanned: Yes Sender: owner-rsgb_lf_group@blacksheep.org Precedence: bulk Reply-To: rsgb_lf_group@blacksheep.org X-Listname: rsgb_lf_group X-SA-Exim-Rcpt-To: rs_out_1@blacksheep.org X-SA-Exim-Scanned: No; SAEximRunCond expanded to false x-aol-global-disposition: G x-aol-sid: 3039ac1d605a4bbb05077fd6 X-AOL-IP: 193.82.116.20 X-Mailer: Unknown (No Version) --_000_BF4A524700075746A6467658DFC7102C19A043E51EICTSSEXC2CAlu_ Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable Stefan, about high efficiency switched PA's: do you have any LPF between PA and an= tenna ? This would require some quite impressive inductors in the mH range at 50= Ohm. Going to lower impedances (8 Ohm) results in more conventient L values, bu= t then you need large capacitors (1-10 uF range, not really a problem) but= impedance matiching may be more critical. Or do you rely on the antenna for harmonic surpression ? 73, Rik ON7YD - OR7T ________________________________ Van: owner-rsgb_lf_group@blacksheep.org [owner-rsgb_lf_group@blacksheep.or= g] namens Stefan Sch=E4fer [Stefan.Schaefer@iup.uni-heidelberg.de] Verzonden: dinsdag 6 april 2010 11:26 Aan: rsgb_lf_group@blacksheep.org Onderwerp: Re: LF: RE: RE: W1VLF 9 Khz Antenna update Putting inductance= near the top. Paul, If you have not yet read much about LF/VLF antennas (for TX) i recommend= the website of Rik/ON7YD: http://www.strobbe.eu/on7yd/136ant/ There, you get all basic necessary informations for becoming QRV on LF/VLF= ! It is published in a understandable way, also with some examples for cal= culations. I have read it several times when i started becoming QRV in 2003 :-) Maybe= you already know many of the informations but it's just nice to read! There is not really a big difference between 137 and 9 kHz if we think abo= ut becoming QRV, except this: Voltages are much more higher Radiation resistances are much lower Inductors needed are much higher (and take much more time to wind ;-) ) Earth losses and coil losses are much higher PA losses are lower (if switched) Propagation on VLF seems to be more efficient Easy to built PAs Lower influence of the skin effect (positive in wires, negative in the ear= th) No limitations of TX power or ERP ;-) ...and so on :-) 73, Stefan/DK7FC Am 05.04.2010 22:35, schrieb Paul A. Cianciolo: Stefan, Thank you for the explanation I will read several more times . To better understand. Thank you again PauLC -----Original Message----- From: Stefan Sch=E4fer [mailto:owner-rsgb_lf_group@blacksheep.org]On Behal= f Of Stefan Sch=E4fer Sent: Monday, April 05, 2010 9:51 AM To: rsgb_lf_group@blacksheep.org Subject: AW: RE: W1VLF 9 Khz Antenna update Putting inductance near the to= p. Paul, There will be a benefit for you, so if it is done easily, do it! When it= can be done easily, why can't you bring up all the L as high as possible? Imagine the E-field lines that come out of the antenna wire. You can imagi= ne that by an analogical example: A garden hose, in the form of the antenna wire construction, with many hol= es in it. Imagine you have a compressor on the bottom and connect the hose= there. The water pressure is equivalent to the voltage, the compressor ha= s the function to increase the pressure; the coil has the function to incr= ease the voltage. The hose diameter is assumed to be very big against the= hole diameter so the pressure is almost the same at each part of the hose= (even at the end). Your goal is to bring as much water (water [liters]is= here equivalent to electrical charge [As](absolute value)) as possible th= rough the vertical part of the hose without loosing to much on the way to= the top. This is because, in the electrical case, you want to fed as much= current as possible through the radiation resistance to radiate the power= I^2*Rrad. The water (charge) that comes out of the hose in the vertical= part before reaching the maximum vertical height is not crossing the uppe= r part of the radiation resistance and thus the ERP is smaller. So, it is= the best to place the compressor/coil as high as possible since if the pr= essure/voltage in the vertical section is smaller (like before the compres= sor/coil) there is not so much water pressed through the holes in the vert= ical section! And if you increase the horizontal section of the construction, there are= more holes in sum above the compressor and thus more water is pressed thr= ough them at a given pressure. So, the more holes the more water, or charg= e (=3Dcurrent per cycle) in the vertical part. This analogical model can explain even more but surely there are also thin= gs that cannot be compared (like a AC water flow ;-); no closed circuit...= ). But for a first imagination it is useful in my point of view ;-) If you place all the L on the tower it will be optimal. Then, you could us= e a simple wire that connects to your earth system without the need for a= distance to other metallic parts, since there is no HV on this wire any= more! That makes it easier even more! You can inject the power by applying a isolated primary on the coil and co= nnect it to your PA in the shack by a loudspeaker cable. Or you need a tra= nsformer and inject it on the bottom of the wire between earth and lower= part of the coil. That may be even a litte easier... A later step will be to reduce the earth resistance but you can do that af= ter starting to come up on the band since there will be no changes to the= coil, maybe just to the output ratio of the PA transformer. Which PA will= you use? Best 73 and much fun! Stefan/DK7FC ________________________________ Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Paul A. Cianciolo Gesendet: So 04.04.2010 22:28 An: rsgb_lf_group@blacksheep.org Betreff: LF: RE: W1VLF 9 Khz Antenna update Putting inductance near the to= p. Stefan On page 60 and 61 of the Low Frequency Experimenters Handbook Peter Dodd= RSGB there is an example putting a coil near the top of the antenna In this case the transmitter is on 137 Khz and a of a portion (1/2) of the= "L" needed to resonate was moved near the top. According to measurements= by Rik Strobbe ON7YD an increase of 4 to 5 db was measured. Do you think it would be worth the effort to put 1/4 of the total "L" need= ed near the top I could do that very easily. PaulC W1VLF --_000_BF4A524700075746A6467658DFC7102C19A043E51EICTSSEXC2CAlu_ Content-Type: text/html; charset="iso-8859-1" Content-Transfer-Encoding: quoted-printable
Stefan= ,
 
about high efficiency sw= itched PA's: do you have any LPF between PA and antenna ?
This would require some= quite impressive inductors in the mH range at 50 Ohm.
Going to lower impedance= s (8 Ohm) results in more conventient L values, but then you need large ca= pacitors (1-10 uF range, not really a problem) but impedance matiching may= be more critical.
Or do you rely on the an= tenna for harmonic surpression ?
 
73, Rik  ON7YD - OR= 7T
 
Van: owner-rsgb_lf_group@blackshee= p.org [owner-rsgb_lf_group@blacksheep.org] namens Stefan Sch=E4fer [Stefan= .Schaefer@iup.uni-heidelberg.de]
Verzonden: dinsdag 6 april 2010 11:26
Aan: rsgb_lf_group@blacksheep.org
Onderwerp: Re: LF: RE: RE: W1VLF 9 Khz Antenna update Putting induc= tance near the top.

Paul,

If you have not yet read much about LF/VLF antennas (for TX) i recommend= the website of Rik/ON7YD: http://www.strobbe.eu/on7yd/136ant/
There, you get all basic necessary informations for becoming QRV on LF/VLF= ! It is published in a understandable way, also with some examples for cal= culations.
I have read it several times when i started becoming QRV in 2003 :-) Maybe= you already know many of the informations but it's just nice to read!

There is not really a big difference between 137 and 9 kHz if we think abo= ut becoming QRV, except this:
Voltages are much more higher
Radiation resistances are much lower
Inductors needed are much higher (and take much more time to wind ;-) ) Earth losses and coil losses are much higher

PA losses are lower (if switched)
Propagation on VLF seems to be more efficient
Easy to built PAs
Lower influence of the skin effect (positive in wires, negative in the ear= th)
No limitations of TX power or ERP ;-)

...and so on :-)


73, Stefan/DK7FC


Am 05.04.2010 22:35, schrieb Paul A. Cianciolo:
Stefan,
 
Thank you for the explanation I will read several more times .
To better understand.
 
Thank you again
 
PauLC
 
-----Original Message-----
From: Stefan Sch=E4fer [mailto:owner-rsgb_lf_group@blac= ksheep.org]On Behalf Of Stefan Sch=E4fer
Sent: Monday, April 05, 2010 9:51 AM
To: rsgb_lf_group@blacksheep.org
Subject: AW: RE: W1VLF 9 Khz Antenna update Putting inductance near= the top.

Paul,=
 
There will be a benefit= for you, so if it is done easily, do it! When it can be done easily, why= can't you bring up all the L as high as possible?
 
Imagine the E-field lines= that come out of the antenna wire. You can imagine that by an analogical example:
A garden hose, in the for= m of the antenna wire construction, with many holes in it. Imagine you hav= e a compressor on the bottom and connect the hose there. The water pr= essure is equivalent to the voltage, the compressor has the function to increase the pressure; the coil has the function to= increase the voltage. The hose diameter is assumed to be very big against= the hole diameter so the pressure is almost the same at each part of the= hose (even at the end). Your goal is to bring as much water (water [liters]is here equivalent to electrical ch= arge [As](absolute value)) as possible through the vertical part of the ho= se without loosing to much on the way to the top. This is because, in= the electrical case, you want to fed as much current as possible through the radiation resistance to radiate the= power I^2*Rrad. The water (charge) that comes out of the hose in the vert= ical part before reaching the maximum vertical height is not crossing the= upper part of the radiation resistance and thus the ERP is smaller. So, it is the best to place the compressor/c= oil as high as possible since if the pressure/voltage in the vertical sect= ion is smaller (like before the compressor/coil) there is not so much wate= r pressed through the holes in the vertical section!
And if you increase the= horizontal section of the construction, there are more holes in sum above= the compressor and thus more water is pressed through them at a given pre= ssure. So, the more holes the more water, or charge (=3Dcurrent per cycle) in the vertical part.
This analogical model can= explain even more but surely there are also things that cannot be compare= d (like a AC water flow ;-); no closed circuit... ). But for a= first imagination it is useful in my point of view ;-)
 
If you place all the L on= the tower it will be optimal. Then, you could use a simple wire that conn= ects to your earth system without the need for a distance to other metallic parts, since ther= e is no HV on this wire any more! That makes it easier even more!
You can inject the power= by applying a isolated primary on the coil and connect it to your PA in= the shack by a loudspeaker cable. Or you need a transformer and inject it= on the bottom of the wire between earth and lower part of the coil. That may be even a litte easier...
 
A later step will be to= reduce the earth resistance but you can do that after starting to come up= on the band since there will be no changes to the coil, maybe just to the= output ratio of the PA transformer. Which PA will you use?
 
Best 73 and much fun!
 
Stefan/DK7FC
Von: owner-rsgb_lf_group@blacksheep.org im Auftrag von Paul A. Cianciolo Gesendet: So 04.04.2010 22:28
An: rsgb_lf_group@blacksheep.org
Betreff: LF: RE: W1VLF 9 Khz Antenna update Putting inductance near= the top.

Stefan
 
On page 60 and 61 of the Low Frequency Experimenters Handbook Peter Dodd= RSGB  there is an example putting a coil near the top of the antenna=
In this case the transmitter is on 137 Khz and a of a portion (1/2) of th= e "L" needed to resonate was moved near the top. According= to measurements by Rik Strobbe ON7YD  an increase of 4 to 5 db  was measured.
 
Do you think it would be worth the effort to put 1/4 of the total "L= " needed near the top
I could do that very easily.
 
PaulC
W1VLF
 
 
--_000_BF4A524700075746A6467658DFC7102C19A043E51EICTSSEXC2CAlu_--